1. Field of the Invention
This invention relates to a pneumatic structure, and particularly to a puppet-like pneumatic structure which is filled with pressurized fluid such as air or the like to keep a certain shape, and when external force is applied thereto, the outlines of which can be changed.
2. Description of the Prior Art
A structure is generally fabricated by a rigid body, but when a material of rigid body such as metal, resin or the like is used, the costs for fabrication, transportation, installation and the like increase in the case where the fabrication of large-sized structures is intended.
Furthermore, in the case when said structure is installed for decorating, advertising or the like purpose, the installing, dismantling, and transporting operations must be repeated for a comparatively short period of time, so that the costs therefor become enormous.
Moreover, since a driving source having a large capacity and a large-scale driving mechanism are required in the case where such structure a part or the whole of which is constructed in such that it is movable, the structure becomes very expensive, besides the adjustment and maintenance therefor become also difficult. In addition, it is dangerous that one who approaches such structure in order to move the large-sized and heavy structure during the operation thereof.
In view of the above, the present inventor has already proposed a pneumatic structure which is manufactured in such that outlines (external shape) of the structure are fabricated by using a material such as cloth, film or the like through sewing work or the like as a structure main body, inflating the main body as in balloon by the use of a pressurizing means such as blower or the like to define the external shape of said structure, and further providing a simple driving means in the interior of said structure, whereby a part or the whole of the structure can be moved. Said pneumatic structure is disclosed in Japanese Laid-open Utility Model Publication Nos. 124,490/1979 and 117,788/1981, respectively.
In said Laid-open Utility Model Publication No. 117,788/1981, an operation cord is fixed at the point of a bending position and inside the outer skin defining the outlines of the structure, and used as a driving means for moving a part or the whole of the pneumatic structure.
Next, a manner for bending said structure by the use of the operation cord secured to the inside of the pneumatic structure will be described hereinbelow by referring to FIG. 28.
FIG. 28 is a schematic vertical sectional view showing a pneumatic structure having the simplest structure wherein the pneumatic structure 1 is shaped with a cloth or a filmlike material through sewing work. In the example illustrated, said pneumatic structure 1 is shaped into a substantially cylindrical form, and an end of the pneumatic structure 1 is fixed to a pedestal 2. In this condition, when air is supplied to the interior of said pneumatic structure 1 through an air hole 2A defined on said pedestal 2 along the direction of arrow Z, said pneumatic structure 1 takes the external shape (cylindrical form) as shown in FIG. 28.
As shown in FIG. 28, fittings 3 are secured to the inner wall of the pneumatic structure 1, then an operation cord 4 is fixed to said fittings 3, and when said operation cord is pulled along the direction of arrow Y, the pneumatic structure 1 is bent along the direction of arrow P.
In this case, as is apparent from FIGS. 28 and 29, a volume of the pneumatic structure after having been bent decreases remarkably in comparison with that of the pneumatic structure which has not yet been bent. As a result, such pressure inside said structure becomes suddenly high at the time of bending so that force required for the operation cord 4 increases.
Besides, the above-mentioned bending operation cannot be promptly effected.
If such pneumatic structure has a small size, it is possible to bend the structure in accordance with the manner as described above, but when a sectional area in the bending portion of said structure increases, the force required for said operation cord 4 also becomes gradually higher so that the structure cannot be actually bent.
Moreover decrease in said volume is visually apparent and as a result, appearance or impression of said pneumatic structure becomes significantly inferior.
In addition, a position to be bent cannot be fixed, more specifically an axis for bending said pneumatic structure cannot be established at a desired position.
In order to eliminate these various disadvantages, the aforesaid Laid-open Utility Model Publication No. 117,788/1981 discloses a technique wherein a spare cloth is sewed on the side opposite to that is to be bent in the pneumatic structure.
However, the technique of the just above described Laid-open Utility Model Publication has involved the following problems.
Namely, in said Publication, there is merely described a fact of adding spare cloth, but not conditions for fixing the axis for bending the pneumatic structure and the like.
In reality, if the axis of the bending is not definitely established, there is such a fear that a shape of said pneumatic structure (in either bent or upright state) is different from that had been expected, or the shape itself becomes unstable in normal conditions, i.e., where the interior of the structure has been merely filled with a pressurized fluid, and operation cord has not yet been pulled. Thus, there is a case where said structure cannot be bent by means of an operation cord or other driving means as desired.
Furthermore, when the pneumatic structure is shaped into, for example, outlines of human being, animals, imaginary living things or the like (hereinafter referred to simply as "living things or the like") and a part or the whole of said pneumatic structure must be moved, motions of said living things or the like should be more natural and enough in their power of expression. For this reason, there might be such a case where said pneumatic structure is not only bend unidirectionally, but it is required to bent the structure in differently from or opposite to said direction.
Moreover, there is also a case where such a pneumatic structure exhibiting always bending state is intended to either extend or bend in differently from or opposite to said direction.
In Japanese laid-open Utility Model Publication No. 117,788/1981, since the spare cloth is stitched to the main cloth, the stitched portion appears to be a scar when it is exposed to the surface of the main cloth and/or the bent portion is not smooth and is angular, making the appearance poor so that the quality is not sufficiently high for satisfactory use in advertisements or public exhibits.
In this respect, such technique which can respond to the requests as mentioned above has not been disclosed in said both Laid-open Utility Model Publications, and accordingly the developments thereof have been desired.